1. Field of the Invention
The present invention relates to a bit error measuring device for a modem device and a bit error measuring method for the same, which can control a transmission of a test pattern signal by detecting a signal, for example, a CS (Clear to Send) signal of an RS (Request to Send)/CS hardware control signal, which is outputted from a modem device connected with a data processing device through a connector, for example, an RS-232-C connector standardized by Electronic Industries Association, when a data communication flow control is carried out between a communication network and the data processing device.
2. Description of the Related Art
FIG. 4 shows a construction of a typical bit error measuring device for a modem device, which is connected with a data processing device, such as a personal computer, through an RS-232-C connector. The construction of the bit error measuring device will be explained. In FIG. 4, the bit error measuring device comprises a bit error measuring circuit 11, a test pattern transmitting circuit 12 and a clock controlling circuit 13.
The bit error measuring circuit 11 measures (or detects) a bit error in an input signal 11A outputted from a modem device (not shown in the figure), which is a pseudo-random pattern recommended by International Telecommunications Unionxe2x80x94Telecommunication (hereinafter, referred as to ITU-T). The test pattern transmitting circuit 12 outputs a test pattern signal 12A which is a random code recommended by ITU-T, to the outside of the bit error measuring device by synchronizing it with a test pattern synchronizing clock signal 13A outputted from the clock controlling circuit 13. As shown in FIG. 5, the clock controlling circuit 13 divides a basic clock signal by using a dividing circuit 15 and generates the test pattern synchronizing clock signal 13A to output it to the test pattern transmitting circuit 12.
According to the bit error measuring device as shown in FIG. 4, the test pattern transmitting circuit 12 outputs a test pattern signal 12A to the outside of the bit error measuring device by synchronizing it with a test pattern synchronizing clock signal 13A outputted from the clock controlling circuit 13. However, because the bit error measuring device cannot detect a CS signal outputted from the modem device when the flow control is carried out, there is a problem that a control of stopping or retransmitting the test pattern signal to be outputted to the outside of the bit error measuring device cannot be carried out.
The present invention was developed in view of these problems.
An object of the present invention is to provide a bit error measuring device for a modem device or a bit error measuring method for the same, which can detect a signal outputted from the modem device in order to control a test pattern synchronizing clock signal in accordance with the signal outputted from the modem device, and which can carry out a control of stopping or retransmitting a test pattern signal in order to measure (or detect) a bit error when a flow control is carried out by the modem device.
That is, in accordance with one aspect of the present invention, the bit error measuring device for modem device, for measuring bit errors when a flow control operation is carried out, comprises;
a bit error measuring unit for measuring bit errors in an input signal inputted thereinto from the modem device,
a clock controlling unit for outputting a test pattern synchronizing clock signal to a test pattern transmitting unit,
the test pattern transmitting unit for transmitting a test pattern signal when the flow control operation is carried out by the modem device, and
a stop bit detecting unit for outputting a stop bit detecting signal by detecting a stop bit in the test pattern signal transmitted by the test pattern transmitting unit,
wherein the test pattern synchronizing clock signal controls a transmission/stop operation of the test pattern signal on the basis of the stop bit detecting signal outputted from the stop bit detecting unit and a CS signal outputted from the modem device.
According to the above-described bit error measuring device for modem device, the bit error measuring unit measures bit errors in an input signal inputted thereinto from the modem device. The clock controlling unit outputs a test pattern synchronizing clock signal for controlling a transmission/stop operation of the test pattern signal on the basis of the stop bit detecting signal outputted from the stop bit detecting unit and a CS signal outputted from the modem device. The test pattern transmitting unit transmits a test pattern signal when the flow control operation is carried out by the modem device. The stop bit detecting unit detects a stop bit in the test pattern signal transmitted by the test pattern transmitting unit in order to output a stop bit detecting signal.
Because the test pattern signal is stopped or transmitted in accordance with the state of the stop bit, a bit error measurement can be carried out for the modem device when a flow control is carried out by the modem device between a communication network and the data processing device.
The clock controlling unit may comprise:
a start judging unit for outputting a start bit judging signal by judging that a xe2x80x9cHighxe2x80x9d level output is detected in the CS signal outputted from the modem device on the basis of a basic clock signal for setting a timing of each transmission/stop operation of the test pattern signal, and
a stop judging unit for stopping the test pattern transmitting unit from transmitting the test pattern signal on the basis of the stop bit detecting signal outputted from the stop bit detecting unit and the CS signal outputted from the modem device, and for controlling the test pattern synchronizing clock signal so as to retransmit the test pattern signal by the test pattern transmitting unit on the basis of the start judging signal outputted from the start judging unit.
In accordance with another aspect of the present invention, the bit error measuring method for modem device, for measuring bit errors when a flow control operation is carried out, comprises the steps of;
measuring bit errors in an input signal inputted from the modem device,
controlling a transmission/stop operation of a test pattern signal by generating a test pattern synchronizing clock signal on the basis of a stop bit detecting signal and a CS signal outputted from the modem device,
transmitting the test pattern signal when the flow control operation is carried out by the modem device, and
generating the stop bit detecting signal by detecting a stop bit in the test pattern signal.
According to the above-described bit error measuring method for modem device, bit errors are measured in an input signal inputted from the modem device. A transmission/stop operation of the test pattern signal is controlled by generating a test pattern synchronizing clock signal on the basis of the stop bit detecting signal and a CS signal outputted from the modem device. A test pattern signal is transmitted when the flow control operation is carried out by the modem device. A stop bit detecting signal is generated by detecting a stop bit in the test pattern signal.
Because the test pattern signal is stopped or transmitted in accordance with the state of the stop bit, a bit error measurement can be carried out for the modem device when a flow control is carried out by the modem device between a communication network and the data processing device.
The step of control the transmission/stop operation of the test pattern signal may comprise the steps of;
outputting a start bit judging signal by judging that a xe2x80x9cHighxe2x80x9d level output is detected in the CS signal outputted from the modem device on the basis of a basic clock signal for setting a timing of each transmission/stop operation of the test pattern signal, and
stopping of a transmission of the test pattern signal on the basis of the stop bit detecting signal and the CS signal outputted from the modem device, and controlling the test pattern synchronizing clock signal so as to retransmit the test pattern signal on the basis of the start judging signal outputted when it is judged that the xe2x80x9cHighxe2x80x9d level output is detected.
In accordance with another aspect of the present invention, the bit error measuring device for modem device, comprises;
a bit error measuring unit for measuring a bit error in an input signal from the modem device,
a clock controlling unit for controlling an output of a clock signal on the basis of a control signal outputted from the modem device, and
a test pattern transmitting unit for transmitting a test pattern signal by synchronizing with the clock signal when clock pulses of the clock signal are outputted from the clock controlling unit, and for stopping a transmission of the test pattern signal when the clock pulses of the clock signal are not outputted from the clock controlling unit.
In accordance with another aspect of the present invention, the bit error measuring method for modem device, comprising the steps of;
measuring a bit error in an input signal from the modem device,
controlling an output of a clock signal on the basis of a control signal outputted from the modem device, and
transmitting a test pattern signal by synchronizing with the clock signal when clock pulses of the clock signal are outputted, and stopping a transmission of the test pattern signal when the clock pulses of the clock signal are not outputted.